1. Field of the Invention
This invention relates to an improvement to an antitheft lock assembly to be used with an object to be protected against theft, which may be a personal computer or some other expensive commodity having an engaging slot cut through the wall of the housing thereof, of the type having a lock main body including a cylinder that comprises a rotary hook shaft such that, as the rotary hook shaft is inserted into the engaging slot and the cylinder lock is operated with a matching key, the extreme anchor section of the rotary hook shaft is made unremovable from the object through the engaging slot to prevent the object from being wrongfully taken away if the wire rope extending from the lock main body is wound around a pillar or some other immovable object on the site.
2. Prior Art
Various lock assemblies of the type under consideration have been proposed, including those that are currently commercially available (as the one disclosed in U.S. Pat. No. 5,327,752). They typically comprise a lock main body 1 and a binding wire rope 2 extending from it as shown in FIG. 7 of the accompanying drawings. The stranded wire 2a of the wire rope 2 has a loop 2c at the front end thereof with a fixture 2b fitted to the root of the loop 2c. The lock main body 1 may or may not be made to pass through the loop 2c before the binding wire rope 2 is secured to an immovable object such as a pillar of the building by means of the loop 2c, while the lock main body 1 is unremovably inserted into and secured to an engaging slot H arranged in the object B to be protected against theft, which may be an expensive commodity for sale such as a portable computer, once it is locked as will be described hereinafter.
Referring to FIG. 7, the lock main body 1 comprises a cylinder lock 1A of a known type constituted by a cylindrical outer shell 1a, a cylindrical inner shell 1b and a pin tumbler 1c (not shown) and an aligning cap 3 covering a rear portion of the cylindrical outer shell 1a from behind in such a way that it is axially and outwardly slidable relative to the cylindrical outer shell 1a by distance S. Additionally, as shown, a rotary hook shaft 1d axially extends from the rear end of the cylindrical inner shell 1b as integral part thereof.
The rotary hook shaft 1d includes an axial core rod 1f aligned with the lock main body 1 and extending rearwardly through the rear center hole 3a of the aligning cap 3, said rotary hook shaft 1d being adapted to rotate by a predetermined angle of limitation, e.g., 90 degrees, as the matching key is operated in the keyhole 1e of the cylindrical inner shell 1b, and an extreme anchor section 1g extending perpendicularly relative to the axial core rod 1f.
A pair of anti-revolution arms 4a, 4b are arranged oppositely with the axial core rod 1d interposed therebetween and extend from the rear center hole 3a of the aligning cap 3 to just in front of the extreme anchor section 1g, the distance between the outer peripheral edges of the paired anti-revolution arms 4a, 4b being substantially equal to the lateral length L of the extreme anchor section 1g. Additionally, a pair of radially extending plate sections 4c are arranged within the aligning cap 3 and extend radially from and perpendicularly relative to the respective anti-revolution arms 4a, 4b to abut a rear end control projection 1i projecting from the rear wall surface 1h of the cylindrical outer shell 1a to confine the revolution of the rotary hook shaft 1d to a predetermined extent. The anti-revolution arms 4a, 4b and the radially extending plate sections 4c constitute an anti-revolution mechanism 4. A spring is disposed between the radially extending plate sections 4c and the inner wall surface 3b of the rear wall of the aligning cap 3.
In the arrangement of FIG. 7, an angle limiting cam 6 is arranged at and engaged with the rear end of the cylindrical inner shell 1b to rotate together by the predetermined control angle as the key is operated. More specifically, the angle of rotation of the cylindrical inner shell 1b is limited by a pair of stopper projections (not shown) arranged on the angle limiting cam 6 as one of the stopper projections abuts the rear end control projection 1i at a time.
The rear surface 6a of the angle limiting cam 6 is held in contact with the front surfaces of the radially extending plate sections 4c under pressure as the latter are urged by the spring 5. At the same time, the aligning cap 3 is also urged by the spring 5 to project rearward by a predetermined length S until the leftmost edge of slide slot 3c of the aligning cap 3 abuts stopper 1j projecting radially from the cylindrical outer shell 1a.
With an antitheft lock assembly having configuration as described above, the lock main body 1 is made to pass through the loop 2c and the stranded wire 2a of the wire rope 2 is wound around a pillar. Then, after ensuring that the paired anti-revolution arms 4a, 4b of the anti-revolution mechanism 4 and the extreme anchor section 1g of the rotary hook shaft 1d are aligned to indicate an unlocked condition of the assembly, they are pushed into the engaging slot H of the object B and the front ends of the anti-revolution arms 4a, 4b are engagedly held in place in the engaging slot H to prevent the lock main body 1 from being unintentionally rotated. Under this condition, the extreme anchor section 1g of the rotary hook shaft 1d should have passed and projecting from the engaging slot H.
Note that the antitheft lock assembly is adapted to accommodate variations in the thickness d of the outer frame of the object B to be protected against theft because the aligning cap 3 is axially movable against the resilient force of the spring 5. Thus, as the key (not shown) is operated to rotate the cylindrical inner shell 1b by the angle of limitation (90 degrees in the illustrated example), the extreme anchor section 1g is also turned to become perpendicular relative to the anti-revolution arms 4a, 4b and puts the assembly into a locked condition. Then, the lock main body 1b cannot be pulled out of the object B, which may be a portable computer or some other expensive commodity, so that it is securely held against theft. Note that, in FIG. 7, reference numeral 7 denotes a flange for preventing the cylindrical inner shell 1b from slipping out of the cylindrical outer shell 1a as it abuts the rear wall surface 1h of the cylindrical outer shell 1a.
In FIG. 7, the base section of the wire rope 2 is firmly secured in a coupling hole 2g running perpendicularly relative to the axis of the lock main body 1 in a rotary coupling section 2f projecting from an annular ring 2e that is rotatably arranged near the front end of the lock main body 1.
More specifically, a coupling sleeve 2h is fitted to the base end 2d of the wire rope 2 and provided at the end thereof with an anti-escape hook 2i that becomes engaged with an anti-escape notch 2j formed on the annular ring 2e as the coupling sleeve 2h is inserted into the coupling hole 2g.
FIGS. 8A and 8B show another known antitheft lock assembly obtained by modifying the assembly of FIG. 7 such that, while the paired anti-revolution arms 4a, 4b extend from the aligning cap 3 through the rear center hole 3a thereof in FIG. 7, the anti-revolution arms of this assembly project from the rear wall of the aligning cap 3.
Thus, as the key is operated in the cylinder lock 1A, the rotary hook shaft 1d including the axial core rod 1f and the extreme anchor section 1g located at the remote end of the axial core rod 1f to show a T-shaped lateral view rotates by 90 degrees from the state shown in FIG. 8A to get into a locked condition as shown in FIG. 8B, where the extreme anchor section 1g is perpendicular relative to the engaging slot H to make it impossible to pull out the lock main body 1 from the object B to be protected against theft.
Currently, various commodities provided with an antitheft arrangement are commercially available. FIGS. 9A and 9B show two typical engaging slots H that can be found in such commodities. In FIG. 9A, the object B to be protected against theft is provided on a wall B1 thereof with a recess B2 for receiving the aligning cap 3 and an engaging slot H is arranged in the recess B2. In FIG. 9B, the object B is provided only with an engaging slot H and the lower end of the slot H is located very close to the bottom surface B3 of the object B.
Anyway, with any known antitheft lock assembly having a configuration as described above, as the anti-revolution arms 4a, 4b projecting from the lock main body 1 are introduced into the antitheft engaging slot H and axial core rod 1f arranged between the anti-revolution arm 4a, 4b is rotated by a predetermined angle by operating the key, the extreme anchor section 1g extending from the axial core rod if to show a T-shaped lateral view is moved from the state aligned with the engaging slot H to an engaged state to make it impossible for the lock assembly to come out from the object B to be protected against theft.
However, the use of a pair of anti-revolution arms 4a, 4b projecting from the lock main body 1 and a T-shaped rotary hook shaft 1d makes the configuration of the antitheft lock assembly rather complicated and costly. Additionally, while the arrangement of a recess and an engaging slot H as shown in FIG. 9A may operate well, a vertically arranged engaging slot H shown in FIG. 9B is accompanied by a drawback that the lower end H1 of the engaging slot H is often located very close to the bottom surface B3 of the object B and therefore, if the lock main body 1 is large relative to the distance h separating the lower end H1 of the engaging slot H and the bottom surface B3 of the object B, which is often very small and placed on top of a desk, the lock main body 1 can be obstructed by the desk top for its operation to make it impossible to properly put the antitheft lock assembly into a locked condition.
In view of the above identified problems of known antitheft lock assemblies, it is therefore the object of the present invention to provide an improved antitheft lock assembly that is free from the above problems. According to a first aspect of the invention, the above object can be achieved by providing an antitheft lock assembly of the type under consideration characterized in that only a single anti-revolution arm is extending from the lock main body and, in the locked state, the rotary hook shaft and the single anti-revolution arm are unrotatably inserted into the corresponding engaging slot of an object to be protected against theft to respectively abut the opposite ends of the slot so that they may not be rickety in the slot and the extreme anchor section is directed toward a lateral side of the anti-revolution arm so as to become retractable through the slot whereas, in the locked state, the extreme anchor section is directed toward a different direction so as to become unremovable through the slot.
Note that the axial core rod and the rotary hook shaft do not show a T-shaped lateral view and the former extends from the front end of the latter only in a direction to provide an L-shaped lateral view.
Thus, with the above arrangement, the components are reduced both in number and dimensions to consequently reduce the cost. Additionally, if the engaging slot is arranged vertically with the lower end located close to the bottom surface of the object to be protected against theft as described above by referring to FIG. 9B, the single anti-revolution arm projects rearwardly below the axial core rod and rests on the lower end of the engaging slot and hence the outer periphery of the lock main body is extended downward only by a limited length from the single anti-revolution arm if compared with any of the above described known antitheft lock assemblies. Thus, the lock main body will not be obstructed for its operation if the lower end of the engaging slot is located very close to the desk top where the object is placed.
According to a second aspect of the invention, in an antitheft lock assembly according to the first aspect, a simple straight rod is used for the anti-revolution arm to reduce the weight of the anti-revolution arm and, in the unlocked state, the extreme anchor section extending from the axial core rod of the rotary hook shaft is located vis-a-vis the inner lateral side of the anti-revolution arm near the free end thereof. With this arrangement, the anti-revolution arm and the extreme anchor section can be inserted into the corresponding engaging slot of an object to be protected against theft with ease and, since the anti-revolution arm is made relatively long, the antitheft lock assembly operates properly if the object to be protected against theft has a large wall thickness.
According to a third aspect of the invention, in an antitheft lock assembly according to the first aspect, the anti-revolution arm includes a base section and a projection projecting from the outer lateral side of the base section to increase the mechanical strength of the anti-revolution arm. According to a fourth aspect of the invention, in an antitheft lock assembly according to the first aspect, the anti-revolution arm includes only a base section to reduce the weight of the lock assembly and make the operation of inserting the rotary hook shaft into the engaging slot easier.
According to a fifth aspect of the invention, there is provided an antitheft lock assembly of the type under consideration characterized in that only a single anti-revolution arm is extending from the lock main body as in the case of an antitheft lock assembly according to any of the first through fourth aspects but, unlike the latter, the rotary hook shaft and the single anti-revolution arm are inserted into the corresponding engaging slot of an object to be protected against theft with a gap found at one or both of the opposite ends of the engaging slot and the anti-revolution arm is located relatively close to the axial core rod of the rotary hook shaft. This arrangement provides the advantage of low cost as in the case of a lock assembly according to the first aspect and, additionally, the rotary hook shaft and the anti-revolution arm can be inserted into the engaging slot with ease. Additionally, the lock main body can be moved upward within the slot by making use of the gap or gaps to avoid the above described problem of obstructing the operation of the lock main body if the engaging slot is arranged vertically and located close to the bottom surface of the object to be protected against theft.
According to a sixth aspect of the invention, in an antitheft lock assembly according to the fifth aspect, a simple straight rod is used for the anti-revolution arm and the extreme anchor section projecting from a lateral side of the axial core rod of the rotary hook shaft is located close to the front end of the anti-revolution arm so that the anti-revolution arm and the rotary hook shaft can be inserted into the corresponding engaging slot of an object to be protected against theft. According to a seventh aspect of the invention, in an antitheft lock assembly according to the fifth aspect, a relatively long and simple rod is used for the anti-revolution arm and the extreme anchor section laterally extending from the axial core rod of the rotary hook shaft is projecting in a direction opposite to the anti-revolution arm projecting from the engaging slot. This arrangement can accommodate an object to be protected against theft if the latter has a relatively thick wall.